An innovative new subsea water-injection treatment system is due to undergo full-scale pilot plant trials on the seabed early this month.
Well Processing’s SWIT (subsea water-injection treatment) field trial project has been co-ordinated by Aberdeen-based ITF (Industry Technology Facilitator) and has received financial support from several international oil companies.
The industry funding co-ordinated by ITF also allowed Well Processing to secure further money from Norway’s Demo 2000 technology development support scheme.
This is the first time that the two bodies have worked in conjunction to secure support for a joint industry project (JIP).
Injecting seawater into reservoirs for maintenance of reservoir pressure and increased oil recovery (IOR) is a long established and common practice. Treatment of the water before injection is essential to avoid plugging and souring of the reservoir.
Offshore, water treatment equipment and high-pressure pumps are traditionally located on platform topsides.
The treated seawater is injected into the main field reservoir through platform-based injection wells, or can be transported out to subsea injection wells through long flowlines.
While this approach has served the industry for many years, it does impose some limitations with respect to how a field can be most effectively drained, including:
The number of well slots made available for seawater injection will affect the field drainage strategy and efficiency.
The treatment plant itself can restrict the amount of seawater available.
Limited reach from the platform can also be an issue.
Large, heavy treatment plants are costly and operator-intensive to run.
Well Processing’s technology manager, David Pinchin, believes that what SWIT will offer the offshore industry is significant.
“The underlying motivation for the development of this technology was to give reservoir engineers the freedom to think outside the box,” said Pinchin.
“Because a topsides water treatment and injection plant is reliant on the data gathered from initial appraisal well information, it may be inadequate for the field’s needs over its entire lifetime. SWIT gives freedom of choice with respect to the number and location of injection wells – it allows for injection of as much treated seawater as required, where required – without typical host platform restrictions.
“This technology will essentially allow the decision on water-injection needs to be delayed until the reservoir is up and running – operators can see how a reservoir reacts then provide water injection as required rather than having to estimate future requirements and design them into the platform at the outset. Other applications for SWIT could be in boosting pressure in older reservoirs, and also in development of satellite fields that would not otherwise be economical.”
The 18-month JIP was launched in December, 2008. However, the treatment technology itself has been under development and testing since 2003.
Since then it has been awarded four patents and won an innovation award at Norway’s Offshore Northern Seas oil show in 2006.
The technology allows for significant reduction in solids content, provides two independent methods for sterilisation of seawater – electro-chlorination and a new method for sterilisation via hydroxyl radical generation – and also includes system sterilisation. The first phase of the project, engineering design and fabrication, is now nearing completion and the pilot plant is due to be transported to NIVA’s marine research centre in Oslofjord for subsea testing.
Once proven, the subsea water-treatment system will be combined with existing subsea water-injection pumping equipment.
ITF’s director of operations, David Liddle, told Energy: “Subsea technology is repeatedly highlighted as an area of interest by ITF’s membership, and it is also an important aspect of the Demo 2000 programme, so I am very pleased that the synergy between the two organisations has enabled this work to be undertaken.
“The technology has a significant contribution to make with respect to increasing oil recovery and maximising production.
“ITF is currently inviting international technology developers to come forward with new proposals to address technology issues associated with the development of subsea long tiebacks in a call that closes on June 30.”
For more information about the SWIT project, contact david.pinchin@ sorco.no. For more information about ITF’s subsea long tiebacks, call go to www.oil-itf.com
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